Recording stylus assembly



April 15, 1958 E. J. KOHN ET AL RECORDING STYLUS ASSEMBLY Filed Dec. 5, 1950 INVENTOR5 KOHN EARL J. GEORGE F. ASBURY SR.

IfATTORNEYS United States Patent 2,830,867 RECORDING STYLUS ASSEMBLY Earl J. Kohn and George Franklin Asbury, Sr., Washington, D. C.

Application December 5, 1950, Serial No. 199,272

. 4 Claims. (Cl. 346-74) (Granted under Title 35, U. S. Code (1952), see. 266) This invention relates to improvements in the recording stylus assembly used in electrochemical recorders and the like. i

For many purposes, such as the recording of high frequency electrical variations, a sharp and well defined imprint on the recording medium is required to distinguish one cycle from. another. The imprint made with the prior art devices was too rough to be useful at the higher frequencies.

The present invention has made it possible to clearly distinguish the recurrent variations of a given voltage at substantially higher frequencies than any of the known recording device could be satisfactorily operated.

The present invention utilizes a negative electrode insulated from and located adjacent the anode electrode of a conventional recording head. The novel and simple expedient results in an unexpected degreeof improvement in the sharpness of the imprint made on the recording paper.

Accordingly, the object of the present invention is to provide a simple, inexpensive, and novel method and apparatus for increasing the fineness and sharpness of the imprint made on the recording medium of an electrochemical recorder and the like.

Other objects of the present invention will become apparent upon reference to the specification and drawings wherein: s

Figure 1 is a conventional electrochemical recorder system incorporating the novel recording head of the present invention.

Figure 2 is an enlargement of Figure 1 in the vicinity of the recording head.

Figure 3 shows the improvement in the imprint brought about by the present invention.

Figure 4 shows another embodiment of the present invention.

Figure 5 discloses still another embodiment of the present invention.

Figure 6 discloses the instant invention used with the bar shaped anode found in most facsimile recorders.

Referring now to the drawings wherein like reference characters indicate identical or similar elements, an electrochemical recorder is shown which is conventional in all respects except for the recording head comprising electrodes 4, 5 and 5'.

As is well known, an electrochemical recorder generally comprises a series electrical circuit including a cathode member 3 across which the recording paper slides, an anode member 4 located adjacent the cathode 3 but separated therefrom by a chemically treated recording paper 1, a source of voltage 7 to be recorded which represents a given variable, and a source of direct current biasing voltage 8 usually connected in series with the voltage to be recorded. The electrode members 3-4 are in contact with the recording paper.

When the voltage of the anode 4 is raised to a sufliciently high positive value the resultant current passing p 2,830,867 Patented Apr. 15, 1958 through recording paper 1 causes a chemical reaction to take place which causes a visible imprint 10 to appear in the portion of the recording paper 1 adjacent the positive anode electrode due to the oxidation action occurring in the vicinity of the anode.

In practice the voltage of direct current voltage source 8 is not sutliciently high to cause an imprint on recording paper 1 in the absence of a voltage of the correct polarity from signal source 7. No imprint appears on the side of the recording paper 1 adjacent cathode electrode 3, since the connection to the negative terminal of direct current source 8 prevents a sufficiently high positive voltage due to signal source 7 from appearing at cathode 3 to cause a chemical reaction which would cause a visible imprint to appear on the recording paper.

It should be understood that direct current voltage source 8 is not required where the signal voltage source 7 delivers a voltage which drives anode 4 sufliciently positive to cause an imprint on the recording paper 1, and whose negative going portion does not drive cathode 3 sufiiciently positive to effect the recording paper 1.

Rollers 2-2 are provided to move the recording paper between electrodes 3-4.

If signal source 7 delivers a sinusoidal voltage variation, and rollers 2-2 were rotated causing movement of recording paper 1, then a series of dotted areas appear on paper 1 representing the positive peaks of signal voltage variation. As the frequency of the signal increases, a point is reached where succeeding imprints or dots run together as shown in Figure 3a because each dot is not sufiiciently sharply defined.

We discovered however that placing one or more electrodes 5-5, having a negative voltage applied thereto, adjacent but insulated from anode 4 which runs in contact with the recording paper 1 with anode 4, that the imprint on the recording paper became fine and sharp as shown in Figure 3b enabling much higher frequencies to be more clearly and accurately recorded.

This system tends to focus the current resulting in extremely sharp definition of the recorded mark. Essentially, the two outer cathodes tend to buck the center anode thereby concentrating the current in a point. In acutal tests with a sonar range recorder, CAN-55134A the device of this invention, even at maximum voltage of the recorder, provided clear resolution of signals at a frequency more than three times the maximum frequency readable from a standard recording head.

Similar results were obtained with all types of recording paper tested such as Sangamo paper and the paper disclosed in the copending application Ser. No. 191,913, filed October 24, 1950, now Patent No. 2,686,858, patented August 17, 1954.

It is important to note that the cathode electrodes 5-5 should be located laterally of the direction in which the recording paper is moved since the passage of the negative electrode 5-5' over the imprint will erase the imprint. Thus, as shown in Figure 1, the electrodes 5-5 are in a line generally perpendicular of the direction in which recording paper 1 is moved.

In one embodiment, the recording head was made as an integral unit with electrodes 4, 5 and 5' glued to strips of insulation material 6-6. The insulation was made of Bakelite and acted to separate the electrodes from each other. Electrode 4 was made of platinum iridium alloy and electrodes 5 and 5' Weremade of nickel.

The electrodes were .015 inch apart measured between their outer surfaces The anode electrode was .014 inch in diameter (11;) and cathode electrodes 5-5 were .010 inch in diameter (d 1 llThe above dimensions are not critical but are exemplary o y.

It was also discovered that cathode plate 3 need not be used as an electrode element at all but merely as a supporting element. Thus, as shown in Figure 4, electrode becomes the only cathode or negative electrode and the results are surprisingly similar to that described in connection with the embodiment of Figure 1.

Increasing the cathode surface area surrounding anode 4 improves the results obtained with the present invention. Thus cathode electrode 5 could be a generally annular member 5 surrounding anode 4-as shown in Figure 5. Gaps g and g are provided in cathode 5 so that the imprint will not be erased for reasons previously described.

Although the present invention is shown applied to a stylus wherein the anode member has a generally circular cross section, it should be understood that the instant invention has application to' other recording devices such as the well known facsimile recorder utilizing a long bar 4' for the anode as shown in Figure 6. In such case, the cathode electrodes 55"' would be similarly shaped bars running parallel to the anode bar.

Many other modifications may be made of the specific embodiments disclosed in Without deviating from the scope of the present invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalities thereon or therefor.

What is claimed is:

1. A recording head for electrochemical recorders using a traveling electrically sensitive recording medium comprising, an anode electrode and a plurality of cathode electrodes, all of said electrodes being positioned to contact the recording medium, one of said cathode electrodes being positioned on the opposite side of the recording medium from the anode electrode and at least one cathode electrode being further positioned in juxtaposition to said anode electrode and on the same side of the recording medium as said anode electrode.

2. A recording head for electrochemical recorders using a traveling electrically sensitive recording medium comprising, an anode electrode and a plurality of cathode electrodes, all of said electrodes being positioned to contact the recording medium, one of said cathode electrodes being positioned on the opposite side of the recording medium from the anode electrode and at least one cathode electrode being further positioned in juxtaposition to said anode electrode and on the same side of the recording medium as said anode electrode and in transverse relation to the motion of the recording medium.

3. A recording head for electrochemical recorders using a traveling electrically sensitive recording medium comprising, an anode electrode and a plurality of cathode electrodes, all of said electrodes being positioned to contact the recording medium, one of said cathode electrodes being positioned on the opposite side of the recording medium from and directly beneath said anode electrode, and at least one cathode electrode being further positioned in juxtaposition to said anode electrode and on the same side of the recording medium as said anode electrode.

4. A recording head for electrochemical recorders using a traveling electrically sensitive recording medium comprising, an anode electrode and a plurality of cathode electrodes, all of said electrodes being positioned to contact the recording medium, one of said cathode electrodes being positioned on the opposite side of the recording medium from and directly beneath said anode electrode, at least one cathode electrode being further positioned in juxtaposition to' said anode electrode and on the same side of the recording medium' as said anode electrode, and a source of voltage coupled between said anode and cathode electrodes for rendering only said anode electrode sutficiently positive to cause an imprint on said recording medium.

References Cited in the file of this patent UNITED STATES PATENTS 1,558,536 Delany Oct; 27', 1925 1,702,412 Peters Feb. 19, 1929 1,832,237 Noss Nov. 17, 1931 2,462,145 Thomas Feb. 22, 1949 

